Clamp for flexible printing-plates.



J. WHITE.

CLAMP FOR FLEXIBLE PRINTING PLATES.

APPLICATION FILED MAY 17. 1909.

Eatented Sept. 28, 1909.

JOSEPH WHETE, PRESS 6033523..

To all whom it may concern."

Be it known that l, osii zexrof the United State 1 brook, Somerset(aiuuty, State or .a sey, have invented certain new and usefulImprovements in tlamps tor Flexible Printing-Plates, fully described andillustrated in the following specification and accompanying drawing.

The object of this invention l simplify the mechanism for clamping andadjusting the plates to a bed or supporting surface, and to facilitatethe manipulation of the parts so that a plate may be more quickly putin, adjusted to or removed from a printing machine than has beenhitherto possible; and while the device is prii'narily intended to holdflexible printing forms in a printing machine, it also will be used forholding a printing blanket of rubber or other material.

Referring to the drawing in which like characters of reference indicatethe same parts, Figure l is an end view of a printing cylinder showing apair of the clamps to hold a flexible printing plate, one of said clampsbeing in :tion, 4 taken in the direction of the arrow of 1, some of theparts being shown in section.

Referring to Fi 1 a. printing plate 1 of zinc or aluminum is stretch land. adjusted onto the bed 2 by means or hereafter described; this bedlS shown in the form of a segment 2 of a cylinder (although the devicemight be employed in connection with a fiat surface) and has bearing 3formed at its sides against which the clamps reactin order to stretchthe plate on the bed. These bearing faces are former on oneslde ofthegaps reaching across cylinder which have fastened :in them by meansof a series of screws 4, the bearing blocks 5, in which the trunnions(S, of the plate clamps find their bearings.

A plurality of clamps is preferably employed on each end of the plate,although under certain conditions one pair o1 clamps could be used oronFt-lamp conic hold one side of the plate, the other side being held tothe cylinder by any other means. These clamps as illustrated, consist ofa member on which the trunmons G are formed, part of which mcmbcrconslsts oi a web '7 (on the .cnd of which a face 8,} which forms therigid jaw between which and the morabl l ig. 2 is View s to beapplication files 17, E99.

Patented Sept. 28, 1.909.

Serial No. 496,587.

and 13 .upon which is pivoted a member in the form of an angle plate,one wing f) of which extends over the face 8 ot the rigid jaw and actsas the movable jaw of the clamp, the other wing 14 which liesapproximately parallel with the web '1, has a thumb screw 15, whichbears against the web 7 of the clamp and'tends to rock the movable jawon the pivots 12 and 13, thus gripping the sheet between the jaws 8 and9. The function of this screw 15 is to cause the jaws to close asdescribed, but it can be seen that .various devices might be employed tocause reaction between the movable jaw and the fixed jaw, whereby thejaws will close to grip the sheet, but .the device illustrated anddescribed is the-preferable one. \Vhen the sheet is gripped between thejaws, it is then necessary to adjust and strain the plate on thesupporting bed.

The clamp A at the bottom of Fig. 1 is shown in the position of grippingthe sheet, the clamp ll in section in Fig. l is shown open; this clampwill now be rocked i'or- \YZUTII'SO that the plate will be betwccn thejaws of the clamp B, the thumb scrcw will then be manipulated,temporarily cl amping the jaws wer the plate.

in order to properly st -ain the plate to its supporting bed, a devicefor causing a reaction between the hearing face 3 movable jaw is used,which might be constructed in various ways but the prcfcrrcil form isshown; the pivoted jaw has mounted in it the bolt '16 which passesthrough the clearance hole 17 in the fixed jaw and which when turncdwillbear against the face 3 of the printing bed, and force tho,clamp awayfrom it and strain the plate to its surfacc.

lly the peculiar construction, illustrated and shown, it is onlynecessary to lightly set the jaws of the clamp by means of the wingscrews 15, which form an auxiliary means for clamping the platc. The.primary means is applied by the bolt it), which whcu and thc lurncd toforce the (lamp away 'l'rom llH jaws and the plate (due to the tensionapplied by the thumb screw 15) sufficient to hold the plate fromslipping in the jaws.

.It can be seen that the thumb screw 16 has'coiled around its stem, aspiral spring 18,- which is wound .up by the thumb screw when a plate isclamped between the movable jaw and the lower jaw; the friction of thescrew against the body of the clamp is sullicient to prevent it beingunscrewed by the coil spring, but when the bolt 16 is tight cued and thesheet strained to its surface, the stress of the plate in tension causesthe jaw 9 to be rocked slightly on its pivots, and the thumb screw' 16in the wing 'l-l, which has been lightly pressing" against web 7 ol'the. clamp, is released from contact. with web 7, and the spring 18'unwinds to unscrew the thumb screw.

When screws 15 are released from pressure against, the fixed jaws bothsets ol clamps A and B will still hold the plates tightly. and securelyby means of the primary clamping and straining stress described, andwhen it is time to remove the plate when a job is finished, it is onlynecessary to loosen the screws 16 of" the clamps in one of the gapsto'release the grip of all the jaws holding the sheet, thus releasingthe late for removal from the press.

The devices shown in the drawings and described hereinare the preferableforms embodyingthe featuresof this invention; the elements embodying itmay be widely varied in construction 7 without departing from theprinciples specifically mentioned in the Following claims.

The claims:

'1. The combination with a supporting surface for a lleXiblc sheet. of aclamp to grip said sheet. and strain it to the. supporting surface, anda member .in connection with said clamp operating to cause the. clamp togrip and strain the sheet; said clamp so arranged that when said memberis operated to release the strain of the sheet upon the supportingsurface the grip of. the clamp on the sheet will also be released.

2. The combination with a cylindrical supporting surface for a flexiblesheet, of a clamp to grip said sheetand strain it. to the supporting:surface, and a member in connection with said clamp operating to causethe clamp to grip and strain the sheet; said clamp so arranged that whensaid member is operated to release the strain upon the supportingsurface the grip of the clamp'on the sheet willalso be released;

The combination with a supporting surface for a licxible sheet, of apivoted clamp having a pair of jaws to grip the sheet and strain it tothe supporting surface, a member in connection with said clamp ope'ating to rock the clamp to strain the' sheet, and close the jaws togrip the sheet; said clamp ing so arranged that when said member is cperated to release the strain of the sheet upon the supporting surfacethe grip of the jaws on the sheet wili also be released.

4. The combi'natioi'i with a supporting sur- 3 face for a flexiblesheet, of a pivoted clamp to hold said sheet and. strain it to thesupporting surface, said clamp having a ri jaw and a movable jaw; meansappli -e the movable jaw whereby a stress exei ed. to 7; strain saidsheet to the supporting surrace, will also grip the sheet in the jaws ofthe clamp.

5. The combination with a supper 3 Face for a liexible. sheet, of a pairof o; ing clamps, each having a pair of sheet ping jaws. means on eachof the clamps tor causing the jaws to "grip the sheet, means also movingthe clamps tes ers in the sheet to the supporting surface and said 3-means so arranged that when they are open ated to release the strainotthe sheetupon the supporting bed the grip of the wiii' also berelaxed.

(l. The combination with a supportinghed 9 for a flexible sheet, of a.movable ciamp to.

hold said sheet and strain it to the support-- in bed. av hearing,- faceat the end of the bed; said clamp having a rigidjaw a movable jaw. meansapplied to the inovabie jaw ot the clamp and acting against the bearingface, to clamp the jaws and move the clamp to hold and strain the sheet.

7. ,'.lhc combination with a snpport tor a flexible sheet, of a pair ofclamps to hold said sheet and the- .supporting bed, and bearing each endof the bed said clamps eachl a movable jaw and a rigid jaw, means 11.}.3 plied to the movable jaws of each eiamp and acting against thebearingwtaces of the bed, whereby the sheet is ripped between the'clampjaws and the clamp is moved to strain thesheet to the'bed.

St The. combination with a supporting having bearing-faces on itsopposite of a pair of opposing clamps each pair of gripping jaws,actuating meant plied to one ot the jaws of each of posing clamps andacting against. the

faces for causing the jaws to grip sheet and also strain the sheet, tosu porting surface! .aid cl: mps so arrat that when the aetuatingmeansof one t clamps is operated to release the strain at the plate on thebed, the gri of the jaws both clamps will be release 9. The combinationwith a supporting for a flexible sheet, said bed having a. bearing;surface in enchcf a movable clamp, i 1-- ing a rigid jaw and a movabiejaw, auxiliary means acting between the movable jaw and, the rigid jawto hold said sheet in the rip said jaw and primary means actine' betwenithe movable jaw and bearing face or the bed,

whereby the stress exerted to strain said sheetto the supporting bed,will also hold the sheet in the clamp,

10. The combination with a supporting bed for a flexible sheet, said bedhaving hearing faces at either end, of a pair of opposing clamps eachhaving a rigid jaw and a movable jaw, auxiliary means acting between themovable jaw and each rigid jaw of each clamp, to hold said sheet in thegrip of said jaws and primary means acting between the movable jaws andbearing faces of the bed. whereby a stress exerted to strain said sheetto the supporting bed will also hold the sheet in the clamp.

11. The combination of a supporting bed for a flexible sheet, of amovable clamp to hold said sheet and strain it' to the supporting bed,said bed having a bearing 't'aee, said clamp having a rigid jaw and apivoted jaw. a screw in the pivoted jaw moving said jaw to the sheet,another screw in the pivoted jaw, acting against the bearing face formoving the clamps to strain the sheet to its sup porting bed.

vl2. The combination bed for a flexible sheet. of pivoted clamp having arigid jaw and a movable jaw, said supporting bed having a bearing faceat its end, said clamp having a screw acting between the rigid jaw andthe movable jaw to grip the sheet, and another screw on the with asupporting movable jaw acting against the bearing t'ace.

to rock said clamp, to strain said sheet to the supporting bed and alsohold the sheetin the clamp.

13. The combination with a supporting surface for a flexible sheet, of aclamp to grip said sheet and strain it to the supporting surface,primary and auxiliary means on said clamp f0 actuating the sheetgripping means and operating means for the auxiliary means, saidoperating means arranged to re lease the auxiliary means on theapplication of the primary means.

l t. The combination with a supporting bed for a flexible sheet, of amovable clamp to hold said sheet: and to strain it to the supporting bedand a bearing face at the end of the bed; said clamp having a movablejaw and a fixed jaw, auxiliary means acting between the movable jaw andthe fixed jaw to cause the jaws to grip the sheet, and primary meansacting between the movable jaw and the bearing face to cause the jaws togrip the sheet, and means arranged to release the auxiliary means on theapplication of the primary means.

In witness whereof, I have hereunto set my hand in the presence oi twosubscribing witnesses.

JOSEPH XVII ITE.

llitinesses v Lnwis R. Sonornnm, lnnar V. HALL.

